Is There a Limit to Problem Solving?

The restriction will not exclude any real simble systems, in computer or human, in the context of real tasks. A symbol system can state and solve problems because it can generate and test. To solve a problem is to generate a structure using two that satisfies the test of one. Good moves in chess are sought by generating various alternatives and painstakingly evaluating them. How they synthesize a problem space and move generators appropriate to that situation is still on the frontier of artificial intelligence research.